Preparation method of tungsten-rhenium alloy spherical particles

Abstract

The invention discloses a preparation method of tungsten-rhenium alloy spherical particles, which comprises the following steps: dissolving a proper amount of ammonium rhenate in deionized water, then mixing with tungsten powder in proportion, adding into an oil bath reaction kettle, fully stirring and mixing, and simultaneously evaporating to dryness to obtain uniform pressed powder; mashing and sieving the obtained pressed powder, then drying in a vacuum furnace, putting the obtained silt into a crucible, then putting into an atmosphere furnace, and carrying out two-stage reduction to obtain tungsten-rhenium pre-alloyed sand; and S3, the alloy sand is subjected to plasma spheroidizing treatment, and the spherical tungsten-rhenium alloy particles are obtained. The process operability is extremely high, the process is short, large-scale production can be achieved, and the prepared tungsten-rhenium spherical particles are compact, high in sphericity degree, wide in particle size distribution and uniform in rhenium distribution.

Description

Technical Field

[0001] The invention relates to the technical field of tungsten-rhenium particle preparation, and in particular to a method for preparing tungsten-rhenium alloy spherical particles. Background Art

[0002] Tungsten-rhenium alloys can be used to prepare special materials such as electron probes, high-temperature emitters, various cathode materials, coating materials, and target materials. This requires that the rhenium in the tungsten-rhenium alloy has good uniformity, the raw material particle size is controllable and has good fluidity, and even a spherical shape. Since both tungsten and rhenium have ultra-high melting points (3422°C and 3186°C), coarse-grained (>100μm) tungsten-rhenium alloys, especially spherical tungsten-rhenium alloy particles, must rely on ultra-high heat sources such as plasma or electron beams to be prepared under specific processes. Generally, the traditional process for preparing tungsten-rhenium alloy powder cannot simultaneously take into account the uniform introduction of rhenium, a wide range of particle sizes, and good combination of tungsten and rhenium. Summary of the invention

[0003] The invention discloses a method for preparing tungsten-rhenium alloy spherical particles to solve any of the above and other potential problems in the prior art.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: a method for preparing tungsten-rhenium alloy spherical particles, the preparation method specifically comprises the following steps:

[0005] S1) dissolving an appropriate amount of ammonium rhenate in deionized water, then mixing it with tungsten powder in proportion, adding it into an oil bath reactor, stirring and mixing it thoroughly, and evaporating the water to obtain a uniform powder cake;

[0006] S2) crushing the powder cake obtained in S1), sieving it and drying it in a vacuum furnace, placing the obtained powder sand in a crucible and then placing it in an atmosphere furnace for two-stage reduction to obtain tungsten-rhenium pre-alloyed sand;

[0007] S3) Plasma spheroidization treatment is performed on the alloy sand in S2) to obtain spherical tungsten-rhenium alloy particles.

[0008] Furthermore, the ratio of ammonium rhenate to deionized water in S1) is 1-250 g / L, forming an unsaturated solution state; the purity of ammonium rhenate is ≥99.99%;

[0009] The pre-alloyed powder comprises 75wt%≤W≤99wt% and 1≤Re≤25wt% in terms of mass percentage of tungsten and rhenium.

[0010] Furthermore, the purity of the tungsten powder in S1) is ≥99.95%, and the particle size is 40-400 mesh.

[0011] Furthermore, the oil bath temperature in S1) is 100-250°C; and the stirring rate is 100-200 rpm.

[0012] Furthermore, the crushed product in S2) is sieved with a mesh size of ≥40.

[0013] Furthermore, the drying temperature of S2) is 100-120°C; the vacuum degree is less than 10 -3 Pa.

[0014] Furthermore, the specific conditions for reduction in S2) are as follows: the furnace body is a tubular reduction furnace or a box-type reduction furnace, the atmosphere is hydrogen, the two-stage reduction temperatures are 280-350°C and 900-1000°C respectively, the reduction time is 1-3h, and the gas flow rate is 2-5L / min.

[0015] Further, the plasma spheroidization treatment conditions in S3) are: the flow rate of the powder is 15-25g / min; the speed of the powder feeder is 15-20rpm; the plasma power is 37-80Kw; the powder feeding gap is 0.3-0.6mm, and the working atmosphere is a rare gas.

[0016] Furthermore, the density of the tungsten-rhenium alloy spherical particles is ≥98%, the sphericity is ≥95%, and the particle size is ≥400 meshes.

[0017] A tungsten-rhenium alloy spherical particle is prepared by the above-mentioned preparation method.

[0018] The beneficial effects of the present invention are:

[0019] (1) The present invention can prepare spherical tungsten-rhenium alloy particles with a wide particle size range (40-400 mesh): for the first time, this is achieved by controlling the particle size of the tungsten powder raw material and the screening process, and the particle size is highly customized.

[0020] (2) The rhenium content in the tungsten-rhenium spherical particles prepared by the present invention is controllable: by controlling the content of ammonium rhenate, an alloy powder with a free-proportion rhenium content is obtained, the single-particle coating effect is good, and the overall distribution of the rhenium element is uniform, and the product has good scalability.

[0021] (3) The density of the spherical tungsten-rhenium alloy particles prepared by the present invention is ≥98% and the sphericity is ≥95%, and the product quality has a competitive advantage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The microscopic morphology of the tungsten-rhenium alloy sand after hydrogen reduction and the energy spectrum distribution diagram of tungsten and rhenium elements obtained in Example 1 of the present invention are shown.

[0023] Figure 2 This is a laser particle size distribution diagram of spherical tungsten-rhenium alloy particles prepared by Example 2 of the preparation method of the present invention.

[0024] Figure 3This is a low-magnification optical microscope image of spherical tungsten-rhenium alloy particles prepared by Example 2 of the preparation method of the present invention.

[0025] Figure 4 This is a FESEM morphology image of spherical tungsten-rhenium alloy particles prepared by Example 3 of the preparation method of the present invention.

[0026] Figure 5 The FESEM morphology image of the spherical tungsten-rhenium alloy particles prepared by the preparation method of Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments.

[0028] The present invention provides a method for preparing tungsten-rhenium alloy spherical particles, comprising the following steps:

[0029] S1) dissolving an appropriate amount of ammonium rhenate in deionized water, then mixing it with tungsten powder in proportion, adding it into an oil bath reactor, stirring and mixing it thoroughly, and evaporating the water to obtain a uniform powder cake;

[0030] S2) crushing the obtained powder cake, sieving it and drying it in a vacuum furnace, placing the obtained powder sand in a crucible and then placing it in an atmosphere furnace for two-stage reduction to obtain tungsten-rhenium pre-alloyed sand;

[0031] S3) Plasma spheroidization is performed on the alloy sand to obtain spherical tungsten-rhenium alloy particles.

[0032] Furthermore, the ratio of the ammonium rhenate to deionized water in S1 is 1-250 g / L to form an unsaturated solution; and the purity of the ammonium rhenate is ≥99.95%.

[0033] Furthermore, the purity of the tungsten powder in S2) is ≥99.95% and the particle size is 40-400 mesh.

[0034] Furthermore, in said S2), the oil bath temperature is 100-250° C. and the stirring rate is 100-200 rpm.

[0035] Furthermore, the crushed material in S2) is sieved with a mesh size of ≥40.

[0036] Furthermore, the drying temperature of S2) is 100-120°C; the vacuum degree is less than 10 -3 Pa.

[0037] Furthermore, the specific conditions for reduction in S2) are as follows: the furnace body is a tubular reduction furnace or a box-type reduction furnace, the atmosphere is hydrogen, the two-stage reduction temperatures are 280-350°C and 900-1000°C respectively, the reduction time is 1-3h, and the gas flow rate is 2-5L / min.

[0038] Furthermore, the plasma spheroidization treatment conditions in S3) are: the flow rate of the powder is 15-25g / min; the speed of the powder feeder is 15-20rpm; the plasma power is 37-80Kw; the powder feeding gap is 0.3-0.6mm, and the working atmosphere is a rare gas.

[0039] Embodiment 1:

[0040] A tungsten-rhenium alloy spherical particle, with a mass percentage of 75wt% W and 25wt% Re. The preparation method is as follows: Step 1: Dissolve an appropriate amount of ammonium rhenate in deionized water to form a non-saturated solution with a solubility of 250g / L, and then mix it with tungsten powder with a purity of 99.95% and an average particle size of 150 mesh in proportion. Then add it to an oil bath reactor and stir and mix it thoroughly. The oil bath temperature is 180°C; the stirring rate is 150rpm, and the water is evaporated to obtain a uniform powder cake; Step 2: Crush the obtained powder cake and sieve it through 100 mesh, then dry it in a vacuum furnace at a drying temperature of 100°C; the vacuum degree is 10 -3 Pa. The obtained powder sand is then placed in a crucible and then placed in a tubular reduction furnace for two-stage reduction, with temperatures of 320°C and 910°C, a reduction time of 3h, and a gas flow rate of 3L / min. Step 3: The alloy sand is subjected to plasma spheroidization treatment, with a powder flow rate of 16g / min; a powder feeder speed of 20rpm; a plasma power of 67Kw; a powder feeding gap of 0.3mm, and a working atmosphere of rare gas, to finally obtain spherical tungsten-rhenium alloy particles.

[0041] Embodiment 2:

[0042] A tungsten-rhenium alloy spherical particle, with 82wt% W and 18wt% Re by mass percentage. The preparation method is as follows: Step 1: dissolve an appropriate amount of ammonium rhenate in deionized water to form a non-saturated solution with a solubility of 150g / L, and then mix it with tungsten powder with a purity of 99.97% and an average particle size of 40 mesh in proportion. Then add it to an oil bath reactor and stir and mix it thoroughly. The oil bath temperature is 250℃; the stirring rate is 200rpm, and the water is evaporated to obtain a uniform powder cake; Step 2: crush the obtained powder cake and sieve it through 100 mesh and dry it in a vacuum furnace. The drying temperature is 110℃; the vacuum degree is 0.98×10 -3 Pa. The obtained powder sand is then placed in a crucible and then placed in a tubular reduction furnace for two-stage reduction, with temperatures of 305°C and 940°C, a reduction time of 2.5h, and a gas flow rate of 4L / min. Step 3: The alloy sand is subjected to plasma spheroidization treatment, with a powder flow rate of 20g / min; a powder feeder speed of 20rpm; a plasma power of 80Kw; a powder feeding gap of 0.4mm, and a working atmosphere of rare gas, to finally obtain spherical tungsten-rhenium alloy particles.

[0043] Embodiment 3:

[0044] A tungsten-rhenium alloy spherical particle, with 90wt% W and 10wt% Re by mass percentage. The preparation method is as follows: Step 1: dissolve an appropriate amount of ammonium rhenate in deionized water to form an unsaturated solution with a solubility of 80g / L, and then mix it with tungsten powder with a purity of 99.99% and an average particle size of 200 mesh in proportion. Then add it to an oil bath reactor and stir and mix it thoroughly. The oil bath temperature is 180°C; the stirring rate is 150rpm, and the water is evaporated to obtain a uniform powder cake; Step 2: crush the obtained powder cake and sieve it through 150 mesh and dry it in a vacuum furnace. The drying temperature is 100°C; the vacuum degree is 0.81×10 -3 Pa. The obtained powder sand is then placed in a crucible and then put into a box furnace for two-stage reduction, with the temperature at 280°C and 960°C, the reduction time at 1h, and the gas flow rate at 2L / min. Step 3: The alloy sand is subjected to plasma spheroidization treatment, with a powder flow rate of 15g / min; a powder feeder speed of 15rpm; a plasma power of 40Kw; a powder feeding gap of 0.6mm, and a working atmosphere of rare gas, to finally obtain spherical tungsten-rhenium alloy particles.

[0045] Embodiment 4:

[0046] A tungsten-rhenium alloy spherical particle, with 95wt% W and 5wt% Re by mass percentage. The preparation method is as follows: Step 1: dissolve an appropriate amount of ammonium rhenate in deionized water to form a non-saturated solution with a solubility of 1g / L, and then mix it with tungsten powder with a purity of 99.95% and an average particle size of 400 mesh in proportion. Then add it to an oil bath reactor and stir and mix it thoroughly. The oil bath temperature is 250℃; the stirring rate is 100rpm, and the water is evaporated to obtain a uniform powder cake; Step 2: crush the obtained powder cake and sieve it through 200 mesh and dry it in a vacuum furnace. The drying temperature is 120℃; the vacuum degree is 0.74×10 -3 Pa. The obtained powder sand is then placed in a crucible and then put into a tube furnace for two-stage reduction, with the temperature at 350°C and 1000°C, the reduction time at 2h, and the gas flow rate at 5L / min. Step 3: The alloy sand is subjected to plasma spheroidization treatment, with a powder flow rate of 25g / min; a powder feeder speed of 15rpm; a plasma power of 39Kw; a powder feeding gap of 0.5mm, and a working atmosphere of rare gas, to finally obtain spherical tungsten-rhenium alloy particles.

[0047] Test example:

[0048] 1. Powder particle size determination: This test uses a laser particle size distribution instrument to test the powder particle size of the powder obtained in the preparation process. The test method is a wet method.

[0049] 2. Powder morphology characterization: In this experiment, a field emission scanning electron microscope (SEM) of JEOL was used to observe the microscopic morphology of powder sand and spherical particles of tungsten-rhenium alloy after hydrogen reduction.

[0050] First, from Figure 1 It can be seen that, according to the preparation method of this patent, the SEM morphology of the powder obtained in Example 1 after step 2 (S2) shows that after the tungsten powder is mixed with uniform ammonium rhenate, evaporated and dried, the uniformity of rhenium is retained after hydrogen reduction. From the SEM image combined with the surface scanning energy spectrum of rhenium, it can be seen that the powder only has two phases of tungsten and rhenium, and rhenium is well distributed on the surface of tungsten particles (see Figure 1 The statistical spectrum of Re in the lower right corner shows that the detected distribution amount is ≥81% (a small number of particles have poor concave signals, and neither tungsten nor rhenium elements are counted). Therefore, the rhenium uniformity of the tungsten-rhenium alloy powder prepared by the present invention is good, which proves that the rhenium distribution of the present invention is uniform.

[0051] from Figure 2 It can be found that the laser particle size distribution diagram of tungsten-rhenium spherical particles is single-peaked, and the average particle size (D 50 ) is 195μm, which matches the particle size of the tungsten powder raw material used. The particles of the tungsten-rhenium alloy are evenly distributed and of relatively fine size. Combined with the optical microscope image, it is further found that the particle size inheritance of the tungsten-rhenium spherical particles is extremely high. Most of the particle sizes are >200μm, and a few are around 40 mesh (375μm). The particle sphericity is extremely high (>95%), the surface is smooth without satellite balls, and there is obviously no concave pores, and the density is high.

[0052] from Figure 4 and Figure 5 The SEM images of the spherical tungsten-rhenium alloy powder particles with 25wt.% and 10wt.% prepared in Example 1 and Example 3 show that the sphericity of the powder is extremely high (greater than 95%), the particle size is within 50μm and 200μm (can be sieved through 200 mesh and 80 mesh, respectively, matching the particle size of the raw tungsten powder), there is no satellite ball, the particle surface is smooth, and the particle size distribution is narrow. This shows that after the granulated powder is plasma spheroidized, the tungsten-rhenium alloy powder is partially or completely alloyed (a fine grain structure has been formed on the surface of some spheroidized particles).

[0053] The above is a detailed introduction to the preparation method of tungsten-rhenium alloy spherical particles provided in the examples of the present application. The description of the above examples is only used to help understand the method and core idea of ​​the present application; at the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present application.

[0054] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" and "comprising" are open-ended terms, so they should be interpreted as "including / including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the definition of the attached claims.

[0055] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0056] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0057] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be within the scope of protection of the claims attached to the present application.

Claims

1. A method for preparing spherical particles of tungsten-rhenium alloy, characterized in that: The preparation method specifically comprises the following steps: S1) dissolving an appropriate amount of ammonium rhenate in deionized water, then mixing it with tungsten powder in proportion, adding it to an oil bath reactor, stirring and mixing it thoroughly, and evaporating the water to obtain a uniform powder cake; S2) crushing the powder cake obtained in S1), sieving it and drying it in a vacuum furnace, placing the obtained powder sand in a crucible and then placing it in an atmosphere furnace for two-stage reduction to obtain tungsten-rhenium pre-alloyed sand; S3) Plasma spheroidization treatment is performed on the alloy sand in S2) to obtain spherical tungsten-rhenium alloy particles.

2. The preparation method according to claim 1, characterized in that: The ratio of ammonium rhenate to deionized water in S1) is 1-250 g / L, forming an unsaturated solution state; the purity of ammonium rhenate is ≥99.99%; The pre-alloyed powder comprises 75wt%≤W≤99wt% and 1≤Re≤25wt% in terms of mass percentage of tungsten and rhenium.

3. The preparation method according to claim 1, characterized in that: The purity of the tungsten powder in S1) is ≥99.95%, and the particle size is 40-400 mesh.

4. The preparation method according to claim 1, characterized in that: The oil bath temperature in S1) is 100-250°C; the stirring rate is 100-200 rpm.

5. The preparation method according to claim 1, characterized in that: The above-mentioned S2) is crushed and all the ingredients are sieved, and the mesh number of the sieve is ≥40 meshes.

6. The preparation method according to claim 1, characterized in that: The drying temperature of S2) is 100-120°C; the vacuum degree is less than 10 -3 Pa.

7. The preparation method according to claim 1, characterized in that: The specific conditions for reduction in S2) are as follows: the furnace body is a tubular reduction furnace or a box-type reduction furnace, the atmosphere is hydrogen, the two-stage reduction temperatures are 280-350°C and 900-1000°C respectively, the reduction time is 1-3h, and the gas flow rate is 2-5L / min.

8. The preparation method according to claim 1, characterized in that: The plasma spheroidization treatment conditions in S3) are: the flow rate of the powder is 15-25g / min; the speed of the powder feeder is 15-20rpm; the plasma power is 37-80Kw; the powder feeding gap is 0.3-0.6mm, and the working atmosphere is a rare gas.

9. The preparation method according to claim 1, characterized in that: The density of the tungsten-rhenium alloy spherical particles is ≥98%, the sphericity is ≥95%, and the particle size is ≥400 meshes.

10. A tungsten-rhenium alloy spherical particle, characterized in that: The tungsten-rhenium alloy spherical particles are prepared by the preparation method according to any one of claims 1 to 9.

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